Can conservation tillage and residue management enhance energy use efficiency and sustainability of rice-pea system in the Eastern Himalayas?

ABSTRACT

Low productivity and energy use efficiency (EUE) of rice farming are the major concerns for agricultural sustainability in the Eastern Himalayan region of India. A field experiment on rice (Oryza sativa L.)-pea (Pisum sativum L) system was conducted for three consecutive years during 2012–15 in lowland ecosystem to assess the direct and residual impact of tillage and residue management (RM) practises on productivity and sustainability. Significantly higher grain yield of rice was achieved under no-till (NT) than minimum tillage (MT) and conventional tillage (CT). Among RM practises, 50% NPK + green leaf manure, 50% NPK + weed biomass and 50% NPK + in-situ residue retention recorded significantly higher mean grain yields than application of 50% NPK and 100% NPK without residues. Residual effect of MT in preceding rice gave significantly higher green pod yield of succeeding pea than NT and CT. The system EUE was significantly higher under MT (rice)-NT (pea) compared to those of NT-NT and CT-NT systems. The sustainable yield index of rice and pea was maximum under MT-NT followed by NT-NT. Thus, NT/MT with suitable RM practises is a pertinent strategy for sustainable productivity of rice-pea system in the Eastern Himalayas and in similar adjoining regions.     

Comparison of modeling approaches to quantify residue architecture effects on soil temperature and water

RZ-SHAW is a hybrid model, comprised of modules from the Simultaneous Heat and Water (SHAW) model integrated into the Root Zone Water Quality Model (RZWQM) that allows more detailed simulation of different residue types and architectures that affect heat and water transfer at the soil surface. RZ-SHAW allows different methods of surface energy flux evaluation to be used: (1) the SHAW module, where evapotranspiration (ET) and soil heat flux are computed in concert with a detailed surface energy balance; (2) the Shuttleworth–Wallace (S–W) module for ET in which soil surface temperature is assumed equal air temperature; and (3) the PENFLUX module, which uses a Penman transformation for a soil slab under incomplete residue cover. The objective of this study was to compare the predictive accuracy of the three RZ-SHAW modules to simulate effects of residue architecture on net radiation, soil temperature, and water dynamics near the soil surface. The model was tested in Akron, Colorado in a wheat residue-covered (both standing and flat) no-till (NT) plot, and a reduced till (RT) plot where wheat residue was incorporated into the soil. Temperature difference between the soil surface and ambient air frequently exceeded 17 °C under RT and NT conditions, invalidating the isothermal assumption employed in the S–W module. The S–W module overestimated net radiation (R_n) by an average of 69 Wm⁻² and underestimated the 3-cm soil temperature (T_s3) by 2.7 °C for the RT plot, attributed to consequences of the isothermal assumption. Both SHAW and PENFLUX modules overestimated midday T_s3 for RT conditions but underestimated T_s3 for NT conditions. Better performances of the SHAW and PENFLUX surface energy evaluations are to be expected as both approaches are more detailed and consider a more discretized domain than the S–W module. PENFLUX simulated net radiation slightly better than the SHAW module for both plots, while T_s3 was simulated the best by SHAW, with a mean bias error of +0.1 °C for NT and +2.7 °C for RT. Simulation results for soil water content in the surface 30 cm (θ_v30) were mixed. The NT conditions were simulated best by SHAW, with mean bias error for θ_v30 within 0.006 m³ m⁻³; RT conditions were simulated best by the PENFLUX module, which was within 0.010 m³ m⁻³.     

Enhancing the Simplified Surface Energy Balance (SSEB) approach for estimating landscape ET: Validation with the METRIC model

Evapotranspiration (ET) can be derived from satellite data using surface energy balance principles. METRIC (Mapping EvapoTranspiration at high Resolution with Internalized Calibration) is one of the most widely used models available in the literature to estimate ET from satellite imagery. The Simplified Surface Energy Balance (SSEB) model is much easier and less expensive to implement. The main purpose of this research was to present an enhanced version of the Simplified Surface Energy Balance (SSEB) model and to evaluate its performance using the established METRIC model. In this study, SSEB and METRIC ET fractions were compared using 7 Landsat images acquired for south central Idaho during the 2003 growing season. The enhanced SSEB model compared well with the METRIC model output exhibiting an r² improvement from 0.83 to 0.90 in less complex topography (elevation less than 2000 m) and with an improvement of r² from 0.27 to 0.38 in more complex (mountain) areas with elevation greater than 2000 m. Independent evaluation showed that both models exhibited higher variation in complex topographic regions, although more with SSEB than with METRIC. The higher ET fraction variation in the complex mountainous regions highlighted the difficulty of capturing the radiation and heat transfer physics on steep slopes having variable aspect with the simple index model, and the need to conduct more research. However, the temporal consistency of the results suggests that the SSEB model can be used on a wide range of elevation (more successfully up 2000 m) to detect anomalies in space and time for water resources management and monitoring such as for drought early warning systems in data scarce regions. SSEB has a potential for operational agro-hydrologic applications to estimate ET with inputs of surface temperature, NDVI, DEM and reference ET.     

木本能源植物黄连木研究进展

介绍了前人对黄连木生物生态与生理学特性、繁殖与栽培技术、病虫害防治等的研究工作;概述了黄连木的药用价值、用作工艺良材及阿月浑子砧木等用途;并对进一步的研究方向进行了论述.     

能量饲料发芽处理后酶活性变化的研究

本文对三种能量饲料（玉米、大麦、小麦）经发芽处理后，α－淀粉酶，（α＋β）一淀粉酶、蛋白酶、纤维素酶活性变化进行分析研究。结果表明：禾谷类籽实荫发后，酶活性迅速上升，随发芽时间的增长，大麦中纤维素酶活性显著降低，自然晒制后，并不影响酶活性大小，仅幼芽中的酶活性低于发芽后的整粒籽实。     

秸秆应用生物膨化技术制备优质颗粒饲料的研究

介绍一种生物、膨化新技术，目的是使农业秸秆的结构发生变化、淀粉糊化、蛋白质变性、可溶性纤维增加、抗营养因子减少，可制备优质牛羊蛋白颗粒饲料，从而全面提升秸秆的营养价值，扩大秸秆综合利用的途径。     

安徽省粮食作物全素平衡施肥研究

运用土壤养分系统诊断技术对长江流域的小麦，江淮丘陵区域的水稻和淮北平原的玉米进行了全素平衡施肥田间试验。结果表明：采用新的施肥技术与目前通用施肥模式相比，小麦、玉米和水稻分别增产９％～２０％，７％～１６％和６％～１１％。还证实硫肥对淮北玉米有增产效果。采用能量——经济学评价方法对肥料效应进行了系统评估，认为土壤养分系统诊断技术可在安徽省“二高一优”农业中广泛应用     

密度对凡纳滨对虾存活、生长和能量收支的影响

研究了密度(12.04、24.08、48.16、144.49、240.81、337.13、433.46、529.78、626.11尾/m2)对凡纳滨对虾(平均初始湿重0.026±0.006g)存活、生长和能量收支的影响。实验周期45d。结果表明:I.12.04、24.08和48.16尾/m2密度水平对虾的存活率显著高于626.11尾/m2密度水平,但与其它处理差异不显著;II.12.04和24.08尾/m2密度水平对虾的特定生长率显著高于其它处理,特定生长率(SGRd)与密度(D)的回归方程为:SGRd=-0.3911Ln(D) 10.068(R2=0.8745)。     

应用采食模式改进蛋鸡饲喂制度研究

用40周龄 ISA 蛋鸡2116只,随机分为试验组和对照组,同幢鸡舍的2492只为大群组,根据基础日粮,均日喂二次,大群组日喂基础日粮四次,以研究对蛋鸡的影响。结果表明,试验组与对照组的产蛋率、蛋重及蛋的品质均无显著差异,但试验组的饲料成本减少14.74％,主要营养素蛋白质、能量和氨基酸的消耗也分别降低2.17％、2.92％和12.88％。作者认为,蛋鸡对饲料中营养素的利用能力,可能存在“时间节律”性因素的影响。     

小麦灌浆期中光能供求关系模拟与南京地区合理株型的探讨

提出了一个数学模型,对南京地区(32.04°N,118.5°E)小麦籽粒灌浆期中光能供求关系作模拟,以消光系数的日变化为反映株型的指标,从叶水平角随灌浆日进程所应具有的动态表现探讨本地区辐射条件下的合理株型。利用模型对不同基因型的光能利用率作了具体分析。分析表明,在辐射资源不足的南京地区,小麦叶片的水平角随灌浆进程以有一个由直立而水平再至倒垂的动态过程为宜。